1. Field of the Invention
The invention relates to a superconducting magnet, in which a static magnetic filed is generated in a region of interest, i.e. a predetermined volume in which the part under examination has to be placed for imaging.
The invention deals with magnets having a closed current distribution as well as magnets having an open current distribution which are derived from the closed ones.
2. Discussion of Related Art
Real time NMR imaging in a surgical procedure requires open magnets that facilitate access to the surgical area by the surgeon and the surgical instrumentation. Furthermore, a magnet must be designed for a field high enough to achieve an image reconstruction within acceptable time intervals. Such a requirement results in rather larger magnetic structures, particularly in the case of permanent magnets. For high fields, well above 1 Tesla, a magnet design cannot make use of ferromagnetic materials that saturate above 1.5 Tesla, and a design based on permanent magnets with remanences below 1.5 Tesla becomes very inefficient. As a consequence, very high fields are the domain of superconducting magnets and low to medium fields up to a 0.5 Tesla range are now the undisputed domain of permanent magnets.
In the 1 Tesla range, superconducting and permanent magnet technologies can both be used to provide for efficiently generating the magnetic field having the desired strength and homogeneity.
Furthermore both technologies may be combined in designs that take full advantage of both technologies resulting in powerful and efficient new structures.